1.3.3 HTTP Proxy Use
In certain network topologies, the connection from the client to an RPC over HTTP proxy has to go through an HTTP proxy. Thus before establishing a connection to the RPC over HTTP proxy, the client is required to determine whether a HTTP proxy is required to be used.
To do this determination, the client tries sending a message both with and without using an HTTP proxy. If it gets a response without using an HTTP proxy, then it does not use the HTTP proxy for subsequent communication. If it gets a response only by using an HTTP proxy, then it uses the HTTP proxy for subsequent communication.